Rotary jar



Aug. 27, 1935. H. c. coLLETT ROTARY JAR 2. Sheet-s-Sheet l Filed May l5,1955 H. C. COLLETT ROTARY JAR Filed May l5, 1935 2 Sheets-Sheet 2 205%.O0/ 4A V@- iii I z//47 A M ,L

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Patented Aug. 27, 1935 PATENT OFFICE ROTARY JAR Haskell C. Collett, LosAngeles, Calif. Application May 15, 1935, Serial No. 21,510

20 Claims.

My invention relates to a rotary jar used in iishing work in welldrilling, and my invention pertains to a type known as automatic torquecontrol rotary jars. In this type a twist is given to the drill pipe ordrill string after the tool has been secured to a iish, then the upwardtension or pull on the drill pipe causes the tripping of the tool or jarwhen approximately a predetermined upward pull is developed, thus givinga striking blow which may be approximately predetermined.

With this type the force of the blow may be varied by the twist given tothe drill string, together with the tension of the upward pull.

In the above mentioned type of rotary jar my tool embodies the featureof providing for a threaded connection between the drill string ortubing used to support the jarring tool and a fishing tool, thethreading action being transmitted through the jarring tool. In myinvention one of the main objects and :features is the provision of astrong and substan- ,tial upper mandrel having a coarse thread with along lead, the threads being continuous and such 'mandrel being used todevelop a rotating action of a sleeve member within a tubular body, thetubular body being non-rotatably connected to a lower mandrel sub andiishing tool.

Another object and feature of my invention is in requiring a positivepredetermined andrelative rotation between a sleeve actuated by thethreadied mandrel in a turning motion and this sleeve being providedwith end abutting splines coactg ing with complementary splines on alower mandrel connected to the iish. These splines must 85 be rotatedout of end registration to align with the alternate grooves and thusallow the tripping of the jar.

Another feature of my invention resides in the i interconnection of thelower mandrel which is 40 attached to the fish and the slidable bodyhaving the knocking sub by which the lower mandrel and the tubular bodystructure are prevented from relative rotation, these being guided inthe hammer or jarring stroke by these interengaging 46 splines.

Another object and feature of my invention is in the combination of theupper mandrel with the coarse threads of a long lead connected to theupper sub, which in its turn is attached to 50 the drill string, and thelower mandrel sub which is connected to the lower end has the lowermandrel threaded therein. This lower mandrel is provided with a collarforming an anvil. The tubular body is connected to the upper threaded 5lmandrel by a body sub at its upper end and at (Cl. Z-27) its lower endcarries a knocker sub which strikes on the anvil of the lower mandreland gives the jarring action.

With this combination I employ the spline connection of the lowermandrel having the anvil I and the tubular body by sliding constantlymeshing splines and causing the tripping of the jar by a rotatablesleeve which has the end to end registering splines with the lowermandrel which carries the anvil.

A further feature of my invention is the construction for giving aslight rotation of the sleeve, this being by means of interengaging endngers on the upper mandrel which has the coarse threads and the sleeve.This gives a sumcient l5 rotation of the sleeve to disengage the end toend lbearing of the splines and allowing the tripping of the jar.

A further detail feature of my invention is that these end to endabutting splines have surfaces 20 at right angles,'or normal to the axisof the tool and thus are not required to develop any twist, this twistbeing done by the coarse threads on the upper mandrel working inconnection with the upper body sub.

A further detail feature of my invention is providing for the iiow ofthe slushing mud by having a slushing iiuid pipe threaded on the bore ofthe upper threaded mandrel. This pipe extends into the bore of the lowermandrel and has a 30 packed joint seal with the lower mandrel so thatthe slushing mud is forced downwardly directly through the whole jarringtool.

My invention is illustrated in connection with the accompanyingdrawings, in which Fig. 1 is a vertical section through the jarringtool, the upper mandrel, the rotating sleeve and the lower mandrel withthe anvil being shown in elevation;

Fig. 2 is a vertical section through the upper part of the tool abovethe anvil oi' the lower mandrel, showing the upper mandrel and thesleeve in section.

Fig. 3 is a vertical section of the lower part s of the tool connectingwith Fig. 2, and showing the lower mandrel and the anvil connectedthereto in section.

Fig. 4 is a transverse section on the line 4-4 of Figs. 1 and 2, takenin the direction of the 50 arrow.

Fig. 5 is a transverse section on the line i-I of Figs. 1 and 2, takenin the direction of the arrows.

Fig. 6 is a transverse section on the line i--G 5I of Figs. 1 and 2,taken in the direction of the arrows.

Fig. 7 is a vertical section partly broken away to illustrate thetripping action of the butt and splines on the rotatable sleeve and theupper end of the lowermandrel, the body being omitted.

In my invention I employ an upper sub |I which may be connected to adrill pipe or tubing by the ordinary type of threaded connection.Connected to this upper sub I employ an upper mandrel |2, this having athreaded connection preferably by providing the upper sub I| with a boxI3 and the upper end of the upper mandrel with a tapered threaded pinI4, this being a standard threaded connection. 'I'he upper mandrel I2 isprovided with coarse threads I5, these threads preferably beingsubstantially square threads with a long .lead so that considerablemovement endwise is necessary to develop the degree of twist required.Below the threads there is a short neck portion I6 and a lower head I1,this being cylindrical on its periphery and having downwardly projectingngers I8. 'I'hese fingers form part of a cylinder extending downwardlyon their outside from the periphery of the head |1; the inside diameterbeing such that the iingers are of sufficient thickness in a radialdirection to provide adequate strength. The upper mandrel has a bore I9in registry with the bore 20 of the upper mandrel sub I I. i

Threaded on the coarse threads I 5 of the upper mandrel there is a bodysub 2|. This has a squared upper end 22, a cylindrical periphery 23 anda squared lower end 24. It is provided with a tapered thread 25terminating at a lower shoulder 26. The sub is threaded its full lengthand thus has a complete engagement with the full threads I5 on the uppermandrel when the parts are in the position shown in Figs. l and 2, priorto the tripping on the jarring stroke.

A tubular body 30 has a tapered thread 3| at its upper end connectingwith the thread 25 ol the body sub 2| and having its upper end 32abutting against the shoulder 26, these parts when assembled having asoft annular weld 33.

lThe lower end of the tubular body 3U has an internally tapered thread34 extending upwardly from the lower end 35. The knocker sub 36 has anexternally tapered thread 31 from its upper end 38 which is squared,this terminating in a shoulder 39 engaging the end 35 of the tubularbody 30 and at this connection there is a soft annular weld 49. Theknocker sub has a squared lower end 4I; the periphery 42 of the knockersub, the body 30, the body sub 2| and the lower portion of the uppermandrel sub being all the same. The knocker sub 36 has a large internalcylindrical bore dened by the measurement 43. The upper end 38 of theknocker sub form's the hammer of the jar. y

Slidably mounted inv the bore 43 of the knocker sub 36 there is a lowermandrel 45. This has a cylindrical section 46 operating in the bore ofthe knocker sub 36 and at its lower end it is connected to the lowermandrel sub 41. This sub preferably has a tapered threaded box structure48 engaging the externally threaded threads on the pin 49 at thelowerend of the lower mandrel.

This lower mandrel sub 41 is connected to the iishing tool or mayincorporate part of the lishing tool. The lower mandrel has an axialbore 50 for the slushing of mud, which registers with the bore 5I of thelower mandrel sub.

The anvil structure 65 consists of a substantial collar formed integralwith the upper cylindrical portion 46 of the lower mandrel. and this hasa squared anvil shoulder 56. This anvil is cylindrical on its periphery51 but is provided with a number, preferably four, shallow longitudinalgrooves 58 which may be preferably each semicylindrical.

The interconnection between the tubular body 30 and the lower mandrel 45to transmit a twisting action and to give a longitudinal guide duringthe jarring stroke, comprises providing an internally thickened section65 on the body 30. This thickened section has a lower annular shoulder66 and an upper annular shoulder 61. This thickened section is providedwith longitudinal splines 68 (note Fig. 6). In the illustration thesesplines are shown as six in number and these engage with outwardlyextending splines 69 formed integral with the lower mandrel 45 above theanvil 55, there being preferably a short space 10 between the uppersurface of the anvil and the lower edge 1| of the splines 69. In theillustration there are six splines 69 on the lower mandrel. Theseinterengaging splines 68 and 68 transmit the twist or rotational forcesbetween the upper mandrel su'b I| through the medium of the uppermandrel I2, the body sub 2|, the body 30, the lower mandrel 45 to thelower mandrel sub 41.

An important feature of my invention is in the construction and use ofthe loose or rotatable sleeve 15. This sleeve fits inside of the upperportion of the tubular body 30 immediately below the head I1 of theupper mandrel I2 and above the thickened portion 65 having the internalsplines 68. This sleeve is cylindrical on its outside surface and has alower transverse end 16 with an upper end 11 and an inner bore 18 oflarge diameter. The upper portion of the sleeve is provided withlongitudinal fingers 19 which engage between the lingers I8 dependingfrom the head I1 of the upper mandrel I2. Thus by the interengagement ofthese ngers a rotational turn on its axis may be given to the sleeve 15in relation to the body 30 by the rotational action of the upper mandrelI2.

'I'he structure forming the tripping medium between the sleeve and thelower mandrel 45 consists of internal splines extending upwardly fromthe lower portion of the sleeve, that is d from the end 16 (note Figs. 2and 5). These splines have an upper contact end 86 which is designed toengage and contact with the lower contact face 81 of the externalsplines 88 which are formed on the upper portion 89 of the lower mandrel45. These splines 88 and the upper end of the lower mandrel 45 terminateat 90. The contact ends 86 and 81 of the splines on the sleeve and theupper splines on the lower mandrel form an annular surface normal to theaxis of the tool and prior to the tripping for the jarring stroke are inend to end engagement and in alignment as shown in Fig. 5. This leaveslongitudinal spaces 9| extending from the upper end 90 of the lowermandrel 45 to the lower end 16 of the sleeve 15.

The slushing uid connection employs a Wash pipe which has a threadedconnection 96 to the lower end of the upper mandrel I 2 connecting Thiswash pipe nut 91 threaded thus make a water-tight seal where the washpipe enters the bore 50 on the lower mandrel 45, the wash pipe having asliding t in this bore. By this means the slushing mud may be conveyedthrough the jarring tool without any leakage.

In the body at the travel space for the jarring stroke, thatv is betweenthe end 38 of the rocker sub and the anvil shoulder 56, of the anvilcollar 55, I provide perforations to allow discharge of the slushingfluid during the hammer stroke. These allow the slushing fluid to flowoutwardly from the annular space between the lower mandrel and the lowerportion of the body 30. I

provide longitudinal grooves 58 in the anvil collar 55, these being onthe periphery to provide for free flow of the slushing fluid past thisanvil collar.

To facilitate the release or tripping of the butt and splines 85 on thesleeve 15 from the lower end of the splines 88 on the upper portion ofthe lower mandrel 45, I provide a slight rounding |05 on the splines 85at the corners formed by the horizontal upper faces 86 and the verticalradial edges |06. In a complementary manner I form slightly curvedcornersl |01 on the splines 88 formed integral with the lower mandrel 45at the l corners formed by their lower transverse ends 81 lease of thesebutt and splines but prevent breaking down of the metal at thesevertical radial edges of the splines due to the great pressure developedon a comparatively small body of metal.

The manner of operation and functioning of the tool is substantially asfollows: When it is lowered into the well, the various parts are in therelative positions shown in Figs. 1, 2 and 3. When a fish is properlyengaged by the fishing tool the drill string connected to the uppermandrel sub II may be twisted to properly tighten all threaded joints orconnections. This may be done by employing the rotary table throughwhich operates the ordinary kelly of the drill string or with my toolthe drill string may be twisted by tongs. The twist is released byreleasing the rotary table, allowing releasing of the twist incorporatedin the drill pipe. Then an upward pull is exerted on the drill string.As the fish is caught in the hole, that is the bore of the well and thuscannot rotate, the lower mandrel 45, the body 30 and the body sub 2| areheld from rotation. As the upward pull increases the threaded uppermandrel I2 may twist in the body sub 2|. It will be understood that inthis upward pull, the upper ends I I0 of the thickened portions 65 ofthe body and the upper surface of the internal splines 68 engaging thelower end of the sleeve 15, causes a considerable end to end buttpressure on the splines on the sleeve and the A lower surface of thesplines 88 of the upper end mandrel. However, the mandrel is free torotate 2|. -The slight rotation of this upper mandrel I2 causes thefingers I8 on its lower head I1l to operate against the upwardlyextending fingers 19 of the sleeveto rotate the sleeve. Inthis actionthe space formed by the neck I6 between the lower end 24 of the body'sub 2| and the upper surface of the lower head I1 is decreased; butnevertheless the fingers I8 on the upper mandrel I2 and the fingers 18on the sleeve 15 always remain in engagement.

When there is sufficient rotation given to the sleeve to bring thecorners |05 and |01 of the splines 85 and 88 respectively into pressureengagement as illustrated particularly in Fig. '1, the rounded edgestogether with the interengaging threads of the upper mandrel I2 and thebody sub 2|, cause a quick tripping of the splines 85 and 88, releasingthe tool for the jarring stroke. This jar is then given by the contactof the upper or hammer surface 380i the knocker sub 36, strikingtheanvil face 56 of the anvil collar 55 formed integral with the lowermandrel 45. This therefore gives an upward jar on the lower sub 41, thefishing tool and the fish in the well.

The tool is reset by merely lowering the drill string by releasing thetension thereon which gives aflrst longitudinal travel of the body andsleeve relative to the lower mandrel due to the interengagement of thevarious splines and then a rotating action when the upper mandrel I2 isforced downwardly by the weight of the drill string into the body sub2|; this rotating the upper mandrel I2 and the sleeve 15 in a reversedirection to split the splines 85 on the sleeve underneath the lowerends of the splines 88 on the upper end of the lower mandrel. The toolis then in position for another jarring stroke.

If it is found that the jar or hammer action is not sufficiently severe,an initial twist may be given to the drill string, either by the rotarytable or by tongs and the up pull then developed on the drill string.The resistance developedto the relative rotation of the upper bodymandrel I2 and the body sub 2| together with the frictional resistanceof the slipping of the contact ends of the splines 85 and 88, regulatethe tension required in the drill string to cause the tripping of thejar and to give the jarring stroke and hence regulate the force of thisvstroke.

In the jarring stroke the sleeve 15 is carried up with the body as itbears on the shoulder 51. Therefore on the return lowering stroke thesleeve 15 is usually carried to its lowermost positio-n so that thesplines on the sleeve and the upper splines on the lower mandrel maycome Ainto end to end abutting relation. However,

should this not occur an up pull on the drill string with a second orthird slight drop causes the sleeve to slip downwardly so that it may bepositively rotated. In order to reduce the wear -on the shoulder 61, insome cases I employ a hard metal washer IIO.

Various changes may be made in the details of construction withoutdeparting from the spirit or scope of the invention as defined by theappended claims. y

4 I claim:

l. In a rotary jar, the combination of a lower mandrel having an anvilsecured thereto, the lower mandrel having means for connecting to aiish, an upper mandrel having means for connecting to a drill string, abody structure having a slidable connection on the lower mandrel andhaving a hammer member, a rotatable member in the said body having meansinterengaging with the lower mandrel and means actuated by the uppermandrelto rotate the rotatable element to trip the interengaging meansbetween the rotatable element and the lower mandrel to release the jari'or a jarring stroke.

2. A rotary Jar having in combination a lower mandrel having means forconnection to a sh, a tubular body structure slidable but non-rotatablyconnected to the lower mandrel, the lower mandrel having an anvilstructure and the body having a hammer structure, an upper member havingmeans for a rigid connection to a string of drill pipe, a rotatablemember mounted in the body, interengaging restraining means between therotatable member and the lower mandrel to maintain the hammer and anvilapart, and means to rotate the said element by the relative movement oi'the upper member and the body to release the restraining means to effecta jarring stroke between the hammer and anvil members.

3. A rotary jar having in combination a lower member having means forrigid connection to a fish, an upper member having means for a. rigidconnection to a drill string, a body structure slidable butnon-rotatably mounted on the lower. member, the lower member having ananvil structure and the body having a hammer structure, a rotatablemember mounted between the lower member and the body, said rotatablemember and the lower member having interacting restraining means tomaintain the hammer and anvil apart, the upper member having a wedgetype of connection with the body to cause a ositive rotation of theupper member on an upward pull by the drill string, said upper memberhaving means to rotate the rotatable member to disengage the restrainingmeans and permit a jarring blow by the hammer on the anvil. Y

4. A rotary jar having in combination a lower member having Ameans toform a non-rotatable connection to a fish, an upper member having meansforming a rigid connection to a drill string, a body structure slidableby non-rotatably mounted on the lower member, the said body having ahammer and the lower member having an anvil, a rotatable sleeve,interengaging restraining splines on the sleeve and the lower memberadapted to be positioned in end abutting relation, a wedge type ofconnection between the upper member and the body, whereby on an upwardpull on the string, the upper member is rotated, an interconnectionbetween the upper member and the sleeve to rotate the sleeve todisengage the butt end restraining splines and thereby trip the jar andpermit a jarring blow by the hammer o n the anvil.

5. A rotary jar having in combination a lower member having means tor arigid connection to tools to be removed from a well, an upper memberhaving means for rigid connection to a drill string, a body structureslidable but non-rotatably mounted on the lower member, the lower memberhaving an anvil, the body having a hammer, a rotatable member having arestraining structure, the lower member having a complementaryrestraining structure, said structures having contact surfaces at rightangles to the axis of the body, said restraining structures retainingthe hammerand anvil in spaced relation, an interconnection between theupper member and the body to rotate said upper member on an upward pulloi' the drill string, a connection between the upper member and therotatable member to rotate said rotatable member to bring the contactsuri'aces of the restraining structures out of engagement and to permitthe upward movement of the hammer to strike the anvil in a jarring blow.

6. A rotary jar as claimed in claim 5, the connection between the uppermember and the body being such as to cause a reverse rotation of theupper member on loweringof the drill string after a jarring blow, theconnection between the upper member and the rotatable member being suchas to glve a reverse rotation to the rotatable member to bring therestraining structures with their contact facesagain into contact,whereby a second blow may be given by an upward pull on the drillstring. 7. A rotary jar as claimed in claim 5, the connection betweenthe upper member and the rotatable member being such as to permit aslight upward movement of the upper member relative to the body on anupward pull on the drill string, and a slight separation of the uppermember and the rotatable member.

8. A rotary jar having a lower member with means for a rigid connectionto a tool to be loosened from a well, an upper member having means for arigid connection to a drill string, a body slidable but non-rotatablymounted on the lower member, the lower member having an anvil, the bodyhaving a hammer, a rotatable member below the upper member and having alower end. at right angles to the axis ofthe body, the said body havingcomplementary shoulders at right angles to its axis to engage the lowerend of the rotatable member, the rotatable member having a restrainingstructure, the lower member having a complementary restrainingstructure, said structures having end contacts to maintain the anvil andhammer in spaced relation, a wedging type of connection between theupper member and the upper portion of the body to exert an upward pullon the body and a rotational twist to the upper member on an upward pullon the drill string, the upward pull on the drill string transmitting anupward pressure on the lower end of the rotatable member and producing apressure between the contact surfaces of the said restrainingstructures, an interconnection between the upper member and therotatable member to rotate said latter member on the upward pull on thedrill string to bring the contact surfaces of the restraining structureon the rotatable member out of engagement with the contact surfaces ofthe restraining structure on the lower member and thereby trip the jarto give a jarring blow between the hammer and the anvil.

9. A rotary jar as claimed in claim 8, the contact surfaces between therestraining structures on the rotatable member and the lower memberbeing at right angles to the axis of the body.

10. A rotary jar having a lower mandrel with means for a rigidconnection to a tool to be removed from a well, an upper mandrel havingmeans for rigid connection to a drill string, a tubular body slidablybut non-rotatably mounted on the lower mandrel, the body having a hammersurface, the lower mandrel having a collar forming an anvil, a sleeverotatably mounted in the body and surrounding an upper portion of thelower mandrel, the said sleeve and the mandrel each having complementaryrestraining structures with contact surfaces at right angles to the axisof the sleeve and the lower mandrel, said drel having depending fingers,a tubular body restraining structures holding the anvil and hammer inspaced relatign, a wedging type of connection between the upper mandreland the upper end of the body to transmit a pull on the body andarotational twist to the upper mandrel on an upward pull on the drillstring, an interconnection between the body and the sleeve to exert anupward pressure on the sleeve by the upward pull on the body,interengaging means between the upper mandrel and the sleeve to rotatethe sleeve and disengage the contact surfaces of the restrainingstructures on the sleeve and the lower mandrel to thereby trip the jarand permit a jarring blow by the hammer on the anvil.

bring the contact surfaces of the restraining structures on the lowermandrel and the sleeve into engagement.

13. A rotary jar having a lower mandrel with means for a rigidconnection to a tool to beloosened from a well, an upper mandrel havingmeans for a rigid connection to a drill string,.a

body Yhaving a spline connection to the lower mandrel to' permit alongitudinal movement of the body on the lower mandrel but to preventrelative rotational movement, the body having a knocker sub with ahammer surface, the lower mandrel having a collar forming an anvil, aro-l tatable sleeve having restraining splines, the lower mandrel havingcomplementary restraining splines, said splines having endabuttingsurfaces, which when in engagement maintain the hammer andanvilspaced, a wedglng type of connection between the upper mandrel andthe upper portion of the body to develop a pull on the body and arotational twist on the upper mandrel on an upward pull on the drillstring, lnterengaging surfaces between the body and the sleeve to exertan upward pressure on the sleeve during an upward pull on the body,interengaging fingers between the upper mandrel and the sleeve to rotatethe sleeve on rotation ofthe upper mandrel to disengage thecontactsurfaces of the splines on the sleeve and on the lower mandreland thereby trip the jar to give a jarring blow between the hammer andthe anvil, the said splines on the sleeve and the complementary splineson the lower member guiding the sleeve in a rectilinear motion relativeto the lower mandrel during th jarring blow.

14. A rotary jar as claimed in claim 13, the wedging type of connectionbetween the upper mandrel and the body comprising external helical collthreads on the upper mandrel engaging with complementary internalthreads on the upper part 'of the body. l

l5. A rotary jar as claimed in claim 13, the upper and lower mandrelseach having a bore in alignment, a pipe connected to one mandrel andhaving a sliding t in the bore of the other mandrel with a packing toprevent leakage.

16. A rotary jar having an upper mandrel with means for connection to adrill string, said man- 11. A rotary jar as maimed in claim 1o, the

structure having a rotatable wedging connection to the upper mandrel, alower mandrel having a slidable but non-rotatable connection to thebody, the lower mandrel having means for con;.

nection to a fish, a rotatable sleeve in the body having ngers engagingthe fingers of the upper mandrel, the lower 4mandrel and the body havingcomplementary striking surfaces, splines on the sleeve and the lowermandrel, which when in end abutting relation retain the strikingsurfaces apart, the upper mandrel being adapted to develop a slightrotation onan upward pull on the upper mandrel, the said fingerscommunicating a rotation to the sleeve to disalign the splines of thesleeve and the lower mandrel, interengaging means between the body andthe sleeve to exert an upward pressure on the sleeve during an upwardpull on the upper mandrel, whereby on release of the aligned splines ofthe' sleeves and the lower mandrel, a jarring blow is given by th edcorners to facilitate their release at the moment of. tripping the jar.

18. A rotary jar having an upper mandrel with means for attachment to adrill string, a helicoidal thread and annular depending lingers, atubular body having an upper structure with 'a helicoidal threadengaging the thread of the upper mandrel, a transverse shoulder, a lowermandrel in the body, means to prevent relative rotation of the body andthe lower mandrel, but permit longitudinal sliding, contact structuresin the bodyand the lower mandrel to give a jarring blow, the lowermandrel having means for connection to a fish, a housed sleeve in thebody having its lower end bearing on the said shoulder and fingersengagingwith the ngers of the upper mandrel, the sleeve having splines,the upper mandrell having complementary splines, said splines havingcontact surfaces, which when in engagement hold the contact structuresof the body and the lower mandrel spaced apart, whereby an upward pullon the upper mandrel develops a relative rotation of the upper mandreland the sleeve, the upper mandrel by means of the fingers rotating thesleeve to disalign the splines of the sleeve and the lower mandrel, the

lshoulder engagement of the body and the sleeve developing a pressure onthe engaging surfaces of the splines of the sleeve and the lowermandrel, the release of the splines tripping the jar to develop ajarring blow between the said contact structures.

19. A rotary jar as claimed in claim 18, the upperumandrel being adaptedwhen lowered after a jarring blow to have a relative rotation in regardto the body and to ilrst lower the 'sleeve in reference to the lowermandrel and then rotate the sleeve to again align the splines of thesleeve and the lower mandrel.

20. In a rotary jar, a tubular sleeve having a shoulder at the bottom, aplurality of splines, fingers at the top of the sleeve, a lower mandrelhaving splines, the splines of the sleeve and the mandrel having contactsurfaces when in end to end alignment at right angles to the axis of themandrel, the said splines having convexly rounded corners to facilitatetripping of the sleeve in reference to the mandrel at the moment thecontact ends oi' the splines disengage, means to develop an upwardpressure on the sleeve to cause considerable friction for thedisalignment of the said splines, and means operative by an 5 upwardpull to rotate the sleeve in reference to the lower mandrel to disalignthe splines, whereby the splines on the sleeve have an upward slidingmotion relative to the splines of the lower mandrel, the said splinesguiding the sleeve in a rectilineal sliding motion in regard to thelower mandrel.

HASKELL C. COLLETI.

